6-chloro-2-amino-1-methylbenzene-4-sulphonic acid



. anhydride. Thereaction product thus' ob-i Patented Apr; 22,1'1 930 UNITED s'r-A FRANZ HENLEhND BAnTnoLoiuAUs vo's sEN, or HOCHST-OIWTHE-MAIN; eEiiMANY,

' ASSIGNOBS '110 GENERAL ANILINE TION OF DELAWARE worms, mcz, OIFJNEW YORK, N. x, A eoRro 3a-,

e-cHLoRo-ammo-1METHYL];nnzmvna-sorrnonic ACID No Drawing. Original application, filed August 24: 1925, Serial no; 52,21 and in Germany September 1, 1924. Divided and this application The present invention relates to 6-chloro- This application is a division of our copending U. S..patentapplication Ser. No. 52,216 filed August 24, 1925,

We have found that 6-chloro-2-nitro-1- methylbenzene-4-sulphonie acid is obtained by treating 6-chloro-2-nitro-I-ineth lloenzene with sulfuric acid containing sul uric acid tainable consists almost. completely of 6- I chloro-2-nitro-1-methylbenzene J4 sulphonic acid. By reducing the named acid in the usual manner, the hitherto unknown 6-chlor0- 2-amino-1-methylbenzeneA-sulphonic acid; is. obtainedin a state free from isomerides.

The constitution of the said 6-chloro -2-= amino-1-methylbenzene4-sulphonic acid can be positively determined by the elimination: of the amino group and transformation into the known 2-chloro-l-methylbenzenei-sulphonic acid, and by the substitution of chlorine for the amino group, whereby the known 2.6 dichloro 1- -.methylbenzene 4 sulphonic acid is produced;

We have furthermore foundthat one may use in our process as starting materials amixture of 6-chloro-2-nitro-1-methylbenzene and 4:-cliloro-2-nitro-1-methylbenzene as it. is for instance industriall I produced by chlorinating 2-nitro-1-methy benzene. We have found that the. sulphonation of the 6-c hloro-2-nitro- 1-methylbenzene occurs more easily than that of 4-c'hloro-2-nitro-l methylbenzene and that it is ,possible' to carry out the sulphonati on process under such conditions that a su1phonation' of the 6'-chloro 2-nitro-l-methylbenzene is 'efl'ected whereas the 4-ch1oro-2-nitrol-methylbenzene remains unaltered.

The above mentionedfact offers at the same time a new method of separating the 6-ch1oro- 2-nitro-1-methylbenzene from the 4-chlorofiled June 6,1 23. Serial No. 2 3,453.

2 nitro-l-methylbenzene which separation could hi'therto be effected only byfractional it v distillation. o

It is particularly advantageous to subject;

to sulphonation the mixture of '6-chloro-2- nitro-l-methylbenzene' and 4-chloro-2-nitrol-methylbenzene'whicli' is produced during the fractional distillation as a scarcely separable middle fraction; bypartial sulphona-' tion the i-chloro-Q-nitro-l-methylbenzene is isolated almostcompletely in a'technicallyo pure state, whereas the '6-chloro-2-.nitro-lmethylbenzene is converted into the (i-chloro- Q-nitro-1-metliylbenzene-4-sulphonic acid;

A further object of our pres'ent'invention is the particular method of separating the sul-.

phonated portion from the non-sulphonated portion. We have maidethe observation that it is not at all possible to separate in a satisfactory manner the unaltered A-c hloroo-i nitro-l-methylbenzene from the dissolved 6- chloro 2 nitro-lmethylbenzene-flsulphon'ic acidfby pouring the sulphonation mixture into water, because the diluted sulfurlc acid causes a great part of the non-sulphonated; oily- 4-chloro-2-nitro-l-metliylbenz'ene' to be suspendedand even dissolved. \Vhen on the contrary the sodiumv6-chloro-2-nitro-l-meth- I y-lbenzene 4-sulphonate is direetly'salted out,

the non-sulphon'ate'd i-chloro-fl-nit ro-l-methylbenzene is enclosed by the formed crystals,

which renders a-mechanic'al separation impracticable. .l a v The separation of the two substances in question can, however, be effected by carrying out the salting-out operation in two stages namely by'first adding only so 1nucl1 -con ;.mon

salt that. the sodium 6-chloro-2-nitro-l meth- .ylbenzene -sulphonate is not. yet saltedout,

whereas the no'n-sulphonated "4-chlo ro-2- nitro-l-methylbenzene vis thereby practically almost completely "removed from its suspension or: solution. It is only'aft'er the isolation of thenon-sulphonated, oily 4.-chlo1 '0-L-nitrol-methylbenzene which can now be easily effected'that the sodium salt of the 6-chloro-2- nitro-l-methylbenzene-4-su1phonicf acid is salted out-by a further addition of common salt; Also in this case there are still left 2% -'of 4-cli1oro-2-nitro-1 nethylbenzene in the I separated sodium salt of .the 6-cl il0ro-2-nitromethylbenzene and- 4-chloro-2-nitro-1-methylbenzene are run at 7580C., while stirring, 6000 parts of oleum of strength. The

mixture is stirred for another 7-8 hours at the same temperature The sulphonated mixture is then introduced into ,a solution 'of 2500 parts of common salt in 40000 parts of water, care being taken to maintain a temerature of 80 C. which must however not e exceeded. The resulting mass is stirred for sometime and the non-sulphonated, oily 4-chloro-2-nitro-1-methylbenzene is then al- 'zenei-sulphonate of sodium thus separated lowed to separate; it is then separated by draining off whereupon tothe acid aqueous solution are further added, while stirring, 9000 parts of common salt. After cooling, the isolated sodium salt of the 6-chloro-2- nitro-l-methylbenzene--sulphonic acid is filtered by suction.

The yield of 6-chloro-2-nitro 1-methylbenamounts to more than 70% of theory with regard to the original percentage of 6-chloro- 2-nitro-l-methylbenzene. The yield of unaltered 4-chloro-2-nitro-1-methylbenzene is almost quantitative with regard to the original percentage of l-chloro-2-nitro-1-methylbenzene. a

By reducing the 6-chloro-2-nitro11-methy1- benzenei sulphonic acid to 6-chloro-2-amino l-methylbenzene-4-sulphonic acid b the usual methods almost quantitative yiel are obtained.

The 6 -'chloro 2 amino 1 methylbenzene 4-sulphonic acid isa whitish-graypowder, which is sparingly soluble in cold water, readily soluble in hot water. It is soluble in concentrated sulfuric acid to a yellowish sothe 2.6-dichloro-1-methylbenzene-4-sulphonic' lutionfrom whichit is reprecipitated on dilution with water.

chloro- 2-nit ro-l-methylbenzene in the. mixture to be separated being greater than that in the foregoing example, the respective quantities of oleum and common salt must be adequately increased.

e claim:

As a new product, the 6-chloro-2-amino-1- methylbenzene-4-sulphonic acid of the formula:

being a whitish gray powder, sparingly soluble in .cold water, readily soluble in hot water and soluble in concentrated sulfuric acid to a yellowish solution. In testimony whereof, we afix our signatures.

' FRANZ HENLlj].

BARTHOLOMAUS VOSSEN.

By de'aminating the acid, the 6-chloro-1- methylbenzene-4 sulphonic acid is obtained the chloride of which melts at 36 group according to Sandmeyers process,

- acid is obtained, the chloride of which melts at 67 0., the amide at 189 C. and the anilide at 167 C. 4 r

a The separating process as above described is independent within wide limits of the quantitative proportion of the two isomerides; except that in case of the proportion of 6-chloro-2-nitro-l-methylbenzene to the 4-,

C. the amide at 136 C. and the anilideat 94 By substituting chlorine for the amino 

